For I testify that [the Macedonians] gave as much as they were able, and even beyond their ability. Entirely on their own, they urgently pleaded with us for the privilege of sharing in this service to the Lord’s people. 2 Corinthians 8:3-4
“Paul used three key Greek words to describe Christian generosity. First, it is a Christian’s privilege. The Greek word translated “privilege” is charis, the word commonly translated “grace” (see 8:1). The opportunity to give out of one’s wealth is entirely a gift from God. Second, it is sharing of the Christian’s life. The Greek word here is koinonia, the word commonly translated “fellowship.” Just as the Corinthians were sharing in Paul’s ministry by praying for him, the Macedonians knew that by giving they could “share” their great joy for their salvation with other believers. In essence, this is “fellowship”: Christians sharing with each other their enthusiasm for Jesus, their Savior. Finally, Paul described the Macedonians’ giving as a service. The Greek word here is diakonias, the word from which the English word “deacon” is derived. Giving money is a way to serve others.”
Bruce Barton and Grant Osborne in Life Application Commentary: 1 & 2 Corinthians (Wheaton: Tyndale, 1999) 390-391.